1. Field of the Invention
This invention relates to a process and apparatus for the controlled introduction of carbon dioxide into a liquid, especially a beverage. More particularly, this invention relates to the adjustment of the carbon dioxide concentration in a liquid by a process through which the carbon dioxide concentration can be continuously regulated at low levels of carbon dioxide concentration.
2. Discussion Of The Prior Art
It is known to introduce carbon dioxide gas into a liquid flowing through a line by injecting the gas through an injecting device directly into the liquid flowing through a main conveying pipe, or line.
The injecting device can, for example, be a filter candle made of a ceramic material or a sintered metal. Or the injecting device can be a jet-producing system, essentially a nozzle-system, for example of the kind described in the German Offenlegungsschrift No. 1,517,502.
But introducing the gaseous CO.sub.2 directly into the liquid flowing through a main line has the disadvantage that it is difficult to control with precision the resulting concentration of CO.sub.2 in the liquid, particularly if a low concentration is intended. The difficulty is particularly severe if the liquid already contains some CO.sub.2 and the injection of further CO.sub.2 is intended for establishing a precise final concentration in the liquid.
It is an object of this invention to provide a process whereby one can establish and maintain a very desired but precise carbon dioxide concentration in a liquid. It is a further object of this invention to provide such a process which can be accomplished in a convenient, inexpensive manner which does not entail an extensive and complicated device therefore.